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Woo, W.*; Naeem, M.*; Jeong, J.-S.*; Lee, C.-M.*; Harjo, S.; 川崎 卓郎; He, H.*; Wang, X.-L.*
Materials Science & Engineering A, 781, p.139224_1 - 139224_7, 2020/04
被引用回数:39 パーセンタイル:93.25(Nanoscience & Nanotechnology)To elucidate deformation behavior behind the exceptional mechanical properties of CrCoNi based medium entropy alloys, the deformation related microstructural parameters were determined by using in situ neutron diffraction and peaks profile analysis methods. Superior tensile strength and elongation of the CrCoNi alloy is relevant to higher twin fault probability (, up to 3.8%) and dislocation density (, up to 9.7 10 m) compared to those (1.3% and 3.4 10 m, respectively) of the CrCoNiFe at 293K. Meanwhile, at 140K, the of the CrCoNiFe significantly increased up to 4.4% with the stable of 5.0 10 m and its mechanical properties overwhelm those of the CrCoNi at 273K. Such twinning dominant deformation mechanism at low temperature is also assured by lower stacking fault energy (SFE) of the CrCoNiFe at 140K compared to those of the CrCoNi and CrCoNiFe alloys at 293K.
Woo, W.*; Jeong, J.-S.*; Kim, D.-K.*; Lee, C. M.*; Choi, S.-H.*; Suh, J.-Y.*; Lee, S. Y.*; Harjo, S.; 川崎 卓郎
Scientific Reports (Internet), 10(1), p.1350_1 - 1350_15, 2020/01
被引用回数:64 パーセンタイル:94.51(Multidisciplinary Sciences)Stacking fault energies (SFE) were determined in additively manufactured (AM) stainless steel (SS 316 L) and equiatomic CrCoNi medium-entropy alloys. In situ neutron diffraction was performed to obtain a number of faulting-embedded diffraction peaks simultaneously from a set of (hkl) grains during deformation. The peak profiles diffracted from imperfect crystal structures were analyzed to correlate stacking fault probabilities and mean-square lattice strains to the SFE. The result shows that averaged SFEs are 32.8 mJ/m for the AM SS 316 L and 15.1 mJ/m for the AM CrCoNi alloys. Meanwhile, during deformation, the SFE varies from 46 to 21 mJ/m (AM SS 316 L) and 24 to 11 mJ/m (AM CrCoNi) from initial to stabilized stages, respectively. The transient SFEs are attributed to the deformation activity changes from dislocation slip to twinning as straining.